DIELECTRIC PROPERTIES OF LIQUID FOODS AFFECTED BY MOISTURE CONTENTS AND TEMPERATURES | ||||
| Misr Journal of Agricultural Engineering | ||||
| Article 17, Volume 27, Issue 2, April 2010, Page 688-698 PDF (505.07 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/mjae.2010.105937 | ||||
 View on SCiNiTO | ||||
| Author | ||||
| T.H. Ghanem | ||||
| Assoc. Prof., Agric. Eng.. Fac. of Agric., Al-Azhar Univ., Egypt. | ||||
| Abstract | ||||
| The use of microwave energy is of growing interest due to brief time, volumetric heating due to its penetration and reduced processing time, making it an attractive source of thermal energy. The main objective of the present work is to study the effect of milk and tomato, strawberries juices temperatures and moisture contents, dry basis, on dielectric constant, loss tangent, loss factor and penetration depth at 2450 MHz affecting heat and mass transfer by microwave. It was found that the dielectric constant increased by increasing moisture contents, temperatures and increasing the ability of material to store energy. Dielectric constant and dielectric loss factor are exponentially satisfied with coefficients of determinations between0.84-0.91 for tomato and strawberries. The dielectric constant of milk satisfied a linear form with coefficients of determinations between 0.88-0.97. The loss tangent is deceased with increasing the moisture content indicating the energy lost or dissipated by the material, and satisfied a power form with coefficients of determinations ranged between0.75-0.98 for all tested materials. | ||||
| References | ||||
|
Abd El Hameid, El-S.Abd El-H.2001.Mechanization of scalded milk
cream process. PhD. Th. of Ag.Eng. Fuc. ofAgr. Al-Azhar
Univ.
ASAE.1994.Standared, Engineering practice data.ISBNo-929355-50. Lib. of Congress. By Am. Soci. of Ag. Eng:459-466.
Karamas.E.1980 Techniques for measurement of moisture content of foods. Food Tec. April: 52-59.
Lain,G., Harris.C.S,Evens,R. and Waboys,M.1997.Coupled Heat and moisture transfer during vacuum drying. J. Microwave power electromagnetic Energy. 32:34-44. (C.f. Mujamdar, 2001).
Mujamdar,A.S. 2000. Drying technology in agriculture and food science Pub., Inc. Enfield, New Hampshire 03784 U.S.A Ch. 10:253-286.
Mulin,J1995. New method of food preservstion(microwave processing). Blackie Acad.& prof., N. Y.: (C.f. AbdEl Hamid 2000).
Theraja,B.L.1993. A text book electrical technology. Pub. div. of Nirja Constr. & Dev. Co.(p) LTD RAM NAGAR,New Delhi-100055:118-160.
Toledo,R.T.1991.Fudamentals of food process engineering. An AVI book Pub. By Van Nostrand Reinhold.N.Y.10003.ISBN. o-442-23988-6:133-136. | ||||
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